ANESTHETIC MANAGEMENT
Proper timing and coordination are
necessary between the donor organ retrieval team and the transplant center.
Premature induction of anesthesia unnecessarily prolongs the time under
anesthesia for the recipient, whereas delayed induction may jeopardize graft
function by prolonging the period of ischemia.
Patients may receive little advance
warning of the availability of a suitable organ. Many—if not most—will have
eaten a recent meal and should be considered to have a full stomach. Oral
cyclospo-rine must be given preoperatively. Administration of a clear antacid
(sodium citrate), a histamine H2-receptor blocker, and metoclopramide
should be considered. Any sedating premedication may be administered
intravenously just prior to induction.
Monitoring is similar to that used for
other cardiac procedures and is often established prior to induction. Strict
asepsis should be observed dur-ing invasive procedures. Use of the right
internal jugular vein for central access does not appear to compromise its
future use for postoperative endo-myocardial biopsies. A pulmonary artery
catheter is used in many centers for postbypass manage-ment. It need not be
placed in the pulmonary artery before CPB.
A rapid sequence induction may be
performed. The principal objective of anesthetic management is to maintain
organ perfusion until the patient is on CPB. Induction may be carried out with
small doses of opioids (fentanyl, 5–10 mcg/kg) with or without etomidate
(0.2–0.3 mg/kg). A low-dose ketamine– midazolam technique (above) may also be
suitable. Sufentanil, 5 mcg/kg, followed by succinylcholine, 1.5 mg/kg, can be
used as a rapid-sequence tech-nique. Anesthesia is maintained in a similar
fash-ion as for other cardiac operations. A TEE probe is placed following
induction, and antirejection drugs are given.
Sternotomy and cannulation for CPB may
be complicated by scarring from prior cardiac opera-tions. Aminocaproic acid or
tranexamic acid can be used to decrease postoperative bleeding. CPB is
initiated following cannulation of the aorta and both cavae. If a pulmonary
artery catheter was placed, it must be completely withdrawn from the heart with
its tip in the superior vena cava. It must remain within its sterile,
protective sheath if it is to be safely refloated again into the pulmonary
artery following CPB. The recipient’s heart is then excised, allowing the
posterior wall of both atria (with the caval and pulmonary vein openings) to
remain. The atria of the donor heart are anasto-mosed to the recipient’s atrial
remnants (left side first). The aorta and then the pulmonary artery are anastomosed
end to end. The donor heart is then flushed with saline and intracardiac air is
evacu-ated. Methylprednisolone is given before the aortic cross-clamp is
released.
Inotropic support is usually started
prior to separation from CPB to counteract bradycar-dia from sympathetic
denervation. Prolonged graft ischemia may result in transient myocardial
depression. Slow junctional rhythms are common and may require epicardial
pacing. Although the transplanted heart is totally denervated and direct
autonomic influences are absent, its response to circulating catecholamines is
usually normal. The pulmonary artery catheter can be refloated into position
after CPB and is used in conjunction with TEE to evaluate the patient. The most
common post-CPB problem is right ventricular failure from pulmonary
hypertension, which should be treated with hyperventilation, prostaglandin E1 (0.025–0.2 mcg/kg/min), nitric oxide (10–60 ppm),
and an RVAD, if necessary. Bleeding is a common problem because of extensive
suture lines and preoperative hemostatic defects.
Patients will be extubated when they
meet criteria, as with other major cardiac operations. The postoperative course
may be complicated by acute rejection, renal and hepatic dysfunction, and
infections.
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